Implications of the microbiome in pathologies
What is microbiota?
The microbiota is the set of microorganisms (bacteria, archaea, viruses, fungi, and protists) that live inside the human body. There are one trillion microorganisms inside us, a number similar to the number of cells we have, and It is estimated that there are 150 times more microorganisms than genes .
The microbiota contributes genes that have evolved alongside the human genome, leading to improved systemic functioning between both parties, establishing a symbiotic relationship. Microorganisms help regulate intestinal metabolism, strengthen the immune system, protecting humans against pathogens, cooperate in energy acquisition, and maintain the stability of the mucosa. In return, microorganisms can live in our body under favorable conditions for their proliferation, utilizing certain substances as nutrients.
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We refer to the microbiome as the set of microorganisms, genes, metabolites, and environmental conditions in which these microorganisms are found within humans. In other words, the microbiome is the microbial ecosystem, which is concentrated mainly in the gut, lungs, mouth, genitals, eyes, and skin.
Changes in the composition of the microbiota in adults are indicators of chronic illness such as asthma, constipation, gastrointestinal disorders, some types of cancer, degenerative neuronal problems, etc. For this reason, it is important to take good care of our microorganisms by offering them a healthy diet and good daily habits. However, it is important to keep in mind that each person has a different and unique microbiota. Furthermore, the majority of our microbiota is made up of bacteria and appears from the moment we are born, remaining constant until approximately 3 years of age. From this age onwards, the microbiota is subject to continuous changes depending on various factors.
Factors before birth
Many of the microorganisms that make up the future baby's microbiota are of maternal origin, acquired through the placenta or amniotic fluid. The mother's microbiota, in turn, will be influenced by her lifestyle habits; for example, if she suffers from stress, drastic changes in diet, bad habits such as smoking, or even her age. Furthermore, it is known that children born naturally acquire a richer microbiota than those born by cesarean section. This is because the birth canal is essential for the development of microorganisms that will protect the baby against various diseases.
Factors after birth
The breastfeeding period is also considered essential for the establishment of a baby's microbiota, which exhibits significant diversity and greater similarity to the adult microbiota. The environment in which the child grows up is also very important, as sleeping habits, raising pets, diet, and a relaxed social and family environment will all promote microbial diversity. Conversely, the use of antibiotics could harm a baby's microbiota, especially during the first months of life.
Environmental factors
Environmental factors are the main triggers for the health of our microbiota. For example, factors such as stress, fatigue, anxiety, exposure to pollutants, an unbalanced diet, or habits related to smoking or alcohol are harmful to the microbiota and can cause changes in its composition.
Genetic factors
Studies have recently been published in the journal Nature Genetics To evaluate the genetic factors involved in the microbiota, it has been observed that there are some genetic variants that determine the composition of the microorganisms that make up our microbiome. In this regard, an article from the Christian Albrechts University of Kiel found, in the analysis of the DNA of approximately 9,000 people, 38 regions of the genome related to the intestinal microbiota. Within these 38 regions, they detected the AB0 gene responsible for establishing the blood type. This gene determines the specific antigen (A, B, AB, or none) that will be found in the bloodstream and will be released into the intestine when the red blood cell's useful life ends. There, this antigen will be a food source for the microorganisms that inhabit the intestinal tract. Therefore, depending on the blood type, one intestinal environment or another will be generated that will be decisive for the species that make up our microbiota.
In other articles, an association has been observed between variants of the LCT gene, responsible for encoding the enzyme that metabolizes lactose, and the abundance of bacteria of the genus Bifidobacterium in the intestinal microbiota. Furthermore, a relationship has been observed between variants of the FUT2 gene, the DNA that encodes the enzymes that digest blood antigens (A or B), and the abundance of the bacterial genus Ruminococcus.
Likewise, studies have been published with twins to assess the role of genetics in the composition of the species that make up the microbiota. These studies show that identical twins have a more similar microbiota than non-twin or fraternal siblings.
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Thus, genetics once again becomes an essential factor when studying an individual's microbiome and the possible diseases they may suffer, subject to changes in the composition of that microbiome. Precisely, through the genetic tests The composition of microorganisms we have can be studied to evaluate the risk of suffering from certain diseases or the causes of a pathology or illness that affects our health.